Call Management Services (CMS) allow the calling and called parties to exercise control over call set-up functions within a network. Call set-up includes dialing, wait time and time to move through central offices and long distance services. Typically, there are both originating and terminating versions of these Call Management Services. Originating versions address decisions such as which route to take to complete the call, or what action to take upon encountering a busy signal. Terminating versions include the ability to selectively ignore calls, or route them to a handling mechanism. The handling mechanism provides for a treatment for a call and results in an outcome other than a successful call completion to the desired party. It includes, but is not limited to a busy signal, message service, attendant or administrative assistant answering.
Call Management Services are widely deployed in the Public Switched Telephone Network, having been marketed for many years under the acronym CLASSSM, which stands for Custom Local Area Signaling Services. Most private networks, such as Virtual Private Networks (VPN), have deployed proprietary versions of these services, which function in an equivalent manner using capabilities of the current Signaling System 7 (SS7). Virtual Private Networking is a widely deployed generic business service offering which provides customers with a closed user group environment across a plurality of physical locations. There are several subsets of Virtual Private Networking, one of the better-known being Wide Area Centrex (WAC). The CLASS services include Automatic Recall (AR), Automatic Callback (AC), Selective Call Forwarding (SCF), Selective Call Acceptance, Selective Call Rejection (SCR), and the variations thereof. Automatic Callback and Automatic Recall are similar services. Automatic Recall attempts to call back the last party who called the customer, where as Automatic Callback is invoked during an initial attempt by the customer when a busy line is encountered. Automatic Recall is typically not used in private networks since these networks strive to provide a correct disposition for all incoming calls.
Traditional Call Management Services suffer from several serious shortcomings such as:
1) the features are invoked after the network has made major routing decisions, for example, a call is allowed to progress through the network to the called party's line before it is redirected;
2) the features recognize calling and called network interface points or endpoints instead of specific users, making them useless and inappropriate in an environment where users roam amongst a multiplicity of network interface points; 3) the end-to-end signaling capability is limited by antiquated technology; and 4) service portability, the ability to roam while retaining access to personalized CMS features, is not supported.
Several Voice or Video over Internet Protocol (VoIP) telephony solutions have been proposed and/or implemented. However, these solutions tend to emphasize the new capabilities provided by Internet Protocol technology, such as multimedia integration, rather than addressing improvements to existing call-based services. Moreover, these solutions often introduce questionable practices which may undermine the Quality of Service (QoS) to which business customers have become accustomed. Overly aggressive, compression of bandwidth, lack of regard for the scarcity of global Internet Protocol addresses, or alerting the target station or endpoint before call completion is guaranteed are a few examples of some of the issues that result from current solutions.
Therefore, it is desirable to enhance Call Management Services to overcome various shortcomings of the present day services and to extend these enhancements to cover new multimedia calls, without jeopardizing Quality of Service (QoS).